1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus having a cassette-type cleaner for removing contaminant sticking to the surface of a photosensitive medium or a transfer roller.
2. Description of the Related Art
In general, an image forming apparatus applied to a laser printer or the like forms a latent electrostatic image on a photosensitive medium such as a photoreceptor drum or a photoreceptor belt, and the latent electrostatic image is developed using a toner having a predetermined color into a toner image and transferred to a sheet of paper, thereby printing a desired image.
The laser printer is largely divided into a wet type and a dry type according to the toners used. The liquid laser printer employs a developer liquid having a toner mixed with a volatile liquid carrier. The liquid laser printer using such a developer liquid has a better printing quality than the dry laser printer using a powdered toner, and can be protected from harmful toner powder. Thus, this type of developer liquid is increasingly used.
Referring to FIG. 1, the conventional liquid image forming apparatus includes a photoreceptor belt 110 on an endless track, a first transfer roller 121, a second transfer roller 122 and a third transfer roller 123, for circulating the photoreceptor belt 110 in a given path.
Also, there is provided a main charger 135 installed in one side of the photoreceptor belt 110 for charging the surface of photoreceptor belt 110 into uniform charges. In the lower portion of the photoreceptor belt 110, there are provided a laser scanning unit (LSU) 130 for scanning a laser beam onto the photoreceptor belt 110 according to an image signal and forming a latent electrostatic image, and a development device 140 for developing the latent electrostatic image into a toner image by applying a developer liquid composed of a toner having a predetermined color, to a region where the latent electrostatic image is formed. Particularly, in the case of a color printer, there are provided a plurality of laser scanning units (LSUs) 130 for color image implementation and a plurality of development devices each containing a developer liquid having a predetermined color. After the development device 140 develops the toner image, the developer liquid sticking to the photoreceptor belt 110 is dried by a drying roller 151 and a heating roller 152 so that the liquid carrier is removed. Thus, only the toner image developed by the toner, remains on the latent electrostatic image.
The toner image is transferred to a sheet 126 by a transfer roller 124 installed in parallel with the first roller 121 having the photoreceptor belt 110 interposed therebetween. The sheet 126 is fed between the transfer roller 124 and a pressing roller 125 installed in parallel with the transfer roller 124. As described above, the toner image transferred to the sheet 126 is fixed by a separate fixation means (not shown), thereby finally obtaining a desired image.
During the transfer procedure, after the toner image is transferred to the sheet 126, the toner remains on the photoreceptor belt 110. The residual toner may deteriorate printing quality in repetitive printing procedures, thereby resulting in contamination of the system. To remove the residual toner, conventionally, a cleaning roller 160 for cleaning the photoreceptor belt 110 is installed between the transfer roller 124 and the main charger 135 in order to either contact or not contact the surface of the photoreceptor belt 110.
The size of the surface area of the cleaning roller 160 in contact with the surface of the photoreceptor belt 110 is closely related with the contaminant removing efficiency and the life of the cleaning roller 160. Thus, in order to increase the surface area of the cleaning roller 160 in contact with the photoreceptor belt 110, it is preferable to increase the size of the cleaning roller 160 as much as possible. However, increasing the size of the cleaning roller 160 is restricted by the given space of the image forming apparatus. Moreover, a relatively small cleaning roller has a shorter life, and thus, contamination of the photoreceptor belt or an image forming apparatus contiguous to the photoreceptor belt cannot be prevented effectively.